Web Cache Co-ordination Protocol
- The Web Cache Co-ordination Protocol (WCCP), developed by Cisco Systems, specifies interactions between one or more routers (or Layer 3 switches) and one or more web-caches. The purpose of the interaction is to establish and maintain the transparent redirection of selected types of traffic flowing through a group of routers. The selected traffic is redirected to a group of web-caches with the aim of optimizing resource usage and lowering response times.
-- Cisco Systems
In English, WCCP is a way for a cisco router to check that a web proxy is up and where it is so that it can transparently redirect web traffic at it. This way you can force all your users to use the proxy server without touching any client's settings, like you have to with Microsoft IAS, SBS 2000, etc.
This is the idea behind transparent proxying that your ISP uses to confuse your browser. ;)
Should your proxy server fail, the client's connection to the Internet won't be affected. That means you can also take a proxy server off line at any time. You can deploy multiple proxy servers for redundancy.
Traffic is only redirected on port 80.
WCCP v2 allows you to set up WCCP to redirect traffic ports other than 80, can do load distribution, supports MD5 Authentication between each router and each proxy server, and also lets the router bypass the proxy if the proxy rejects packets ("Web Cache Packet Return"). WCCP v2 also allows using the same proxy server (or stack of proxy servers) on a site with more than one connection to the Internet.
Proxy Servers that support WCCP
- Squid v2.3 (supports WCCP v1)
- Squid v2.5 (supports WCCP v1 and v2 1?)
- Squid v2.6 (supports WCCP v1 and v2)
See the 
Squid FAQ.
These are of interest to the WLUG. Of course, there are others.
Proxy Servers that don't support WCCP
Microsoft Proxy or Internet Acceleration Server
1?
- WCCP 2.0 Implementation in Squid 2.5
Following several customer requests, we have completed the required development work for WCCP 2.0 support for Squid version 2.3 and above. At present all Squid versions supports WCCP 1.0.
WCCP 2.0 supports mutliple router and cache server implementations in a network, it also supports MD5 authentication security between the cache server and routers.
Thanks to members of the Squid developer community, this fully integrated enhancement for WCCP 2.0 support is currently in QA, and will be submitted to Squid Open Source in the very near future. The reader may click here to preview the corresponding CVS branch under the Squid source tree.
--Visole Squid Support
